[AT] OT pocket knives

[rlgoss at twc.com]

!!!Dave, All kidding aside, a tape measure is exactly how you get the answer out of measuring an area with a make-shift planimeter. You start tracing an area with the main knife blade resting on a straight line that is drawn outside the area you want to measure.  When you come back to the place on the irregular outline where you started, you measure the perpendicular distance to the straight line. That distance multiplied by the distance between the contact point on one blade and the tip that you use as a tracing pin is a direct read-out of the area. The next time I run into you at a show, I'll give you a live demonstration.  I'm headed to Portersville in a little over two weeks.  Are you going to be there?


Larry
---- Dave Rotigel <rotigel at me.com> wrote: 
> Darn, That's NEAT! I use a tape measure in a similar way!
> 	Dave
> PS, Kidding aside, THAT'S NEAT!
> 
> On Jul 12, 2015, at 11:02 AM, rlgoss at twc.com wrote:
> 
> > I sold both of the polar planimeters I had in our garage sale yesterday.  They were perfectly  good instruments, but technology has left them behind. That fact plus this thread brought to mind that I have carried a two-bladed pen knife for many years specifically because you can use it as a planimeter in an emergency by opening the large blade completely and opening the smaller blade to approximately 90 degrees before starting a tracing. It gives a measure of irregularly-shaped areas that is better than estimations and requires minimal instruments.  You do have to keep the blades sharp so they don't slide sideways over the map, and they need to hinge at opposite ends of the knife.
> > 
> > 
> > Larry
> > ---- jtchall at nc.rr.com wrote: 
> >> Just an update: I bought my son a single blade Case with a plastic/composite 
> >> handle. The knife has a lockback design. After reading your posts it seems 
> >> quite a few folks are using single blade knives instead of the 2 and 3 blade 
> >> knives I carry. I carried him to 3 stores and we tried several. This one is 
> >> fairly easy to open and close, yet the blade is never in a "free" rotating 
> >> state. Some of the easy opening ones seemed to me they could open in your 
> >> pocket. The blade is about 3-3.5 inches long and the knife is big enough to 
> >> get a really good grip on. The handle is also textured. The Kershaw and 
> >> Gerber knives some of you suggested were out of stock actually. Anyway he 
> >> seems pleased and has used it the last couple Saturdays around the farm.
> >> 
> >> John Hall
> >> 
> >> 
> >> 
> >> 
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